Ocean Glow Stick: Sea Worm Emits Strange Blue Glow

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One common sea worm has a rather uncommon trick:
Chaeteopterus variopedatus – also known as the parchment
tube worm for the paperlike tubes it builds for itself and lives
within throughout its life — secretes a bioluminescent mucus that
makes it glow blue.

Now, scientists are a step closer to understanding the mechanisms
behind the worm's glow.

The parchment tube worm can be found on shallow, sandy seafloors
all around the world. Its glow sets it apart from other tube
worms, most of whichdon't glow, and other shallow water
organisms, which typically emit green
light, not blue.

"Shallow water is much more complex than deep water from a
physical standpoint, and green is what organisms see best,"
Dimitri Deheyn, a biologist at the Scripps Institution of
Oceanography involved in the research, told LiveScience's
OurAmazingPlanet. "If you produce light and you want light to be
associated with an ecological function, you want organisms to see
it."

Researchers have known about the unusual blue-glowing worm for
decades, but nobody has ever looked closely at its light-emitting
properties. Now, Deheyn and his colleagues have conducted two new
studies that help characterize it.

First, the team found that, unlike light-emitting mechanisms in
many other organisms, the worm does not require oxygen.

Light production usually occurs when two chemicals react together
with oxygen to produce a compound that then produces light,
Deheyn said. In past studies, researchers have found that glowing
stops in the absence of oxygen.

But when Deheyn's team removed oxygen from the tube worm, the
worm continued glowing. They reported these findings last month
in the journal Physiological and Biochemical Zoology.

"In our case, if you remove oxygen, you don't stop the light,"
said Deheyn. "So the biochemical pathway that eventually leads to
light production does not follow conventional characteristics."

In a separate experiment, the team found that riboflavin— also
known as
vitamin B2 — plays an important role in the worm's light
production, but its exact role remains unclear. However, since
the worms do not produce riboflavin on their own, they must be
acquiring their glowing properties from their diet or from
symbiosis with bacteria, the researchers recently reported in the
journal Photochemistry and Photobiology.

The team still has not determined why the animals emit blue light
or, even more broadly, why they produce light at all. They think
it could be used to lure prey or to ward off predators, but this
remains unclear, they say.

Still, these discoveries bring the researchers closer to
understanding the array of different bioluminescent pathways in
the animal world, of which researchers estimate there could be 20
to 30 varieties, only about three of which have been studied in
detail, Deheyn said.